Base for swivel chair



FIG. 1 is a perspective view of the base for swivel chair from above andone side thereof;

FIG. 2 is a side view of the base for swivel chair viewed directly alongone leg thereof;

FIG. 3 is a top view of the base for swivel chair; and

FIG. 4 is a bottom view of the base for swivel chair.

The ornamental design for a base for swivel chair, as shown.